I had promised to start posting my activations so that others could start planning on how to find me. This weekend, I will be trying to get first on 902 and then 1296. There are just a few stations that will be getting on 902, but they seem to be spread out across local Friday, Saturday and Sunday afternoons. Weather permitting, I will try to work the few on 902 and then move over to 1296. This will not be optimum for stations with limited moon in common to me here in Oregon. Please do not worry that you will miss me. I will be in Oregon until early May.
I need about 15 degrees elevation to get over the near-field rooftops. I will always be on HB9Q when I have internet connectivity. I will likely not stay on until moon set. If you have a special need or want, please send me an email. It is listed at QRZ.com.
Updated – I did not attempt to get on during the 24th local time. The rain was too often and too much. On the 25th, I did get the system assembled and tried to get on 902 MHz. I made a mistake and blew one of my two 902 amplifiers. I need a day or two to finish the modification of the second amplifier. I will be more careful with it. After the final confirmation that the 902 amplifier was dead, I moved over to 1296 MHz. I worked a number of stations including KB2SA for his 49th state. I took a break for dinner, When I came back, the station would not function. I found that the USB hub had failed. I do not have a spare. I will need to replace it before I can try again on 902 and 1296.
For an informal operation, it was a bit of failure and success. I’ll take the success and learn from the failures. More to follow in other posts. Tentatively, I will make a larger effort on 1296 during my local Friday afternoon and evening, March 31 to April 1. This should allow for a better window to EU. I will be at a nearby farm with a much cleaner view of moonrise.
The feed configured for circular polarization is deceptively simple and even easier to put on the air. As shipped, the 90 degree hybrid is labeled for TX and RX.
Here is a comparison photo showing the size difference of the 902 feed versus the 1296 feed as configured for NX9O Rover.
Paul’s feeds are based on patch feeds from SM6PGP. I found a detailed description in a Swedish EME-meeting May 2013 paper, “Circularly Polarized Patch Feed for 1296 MHz”, published by SM6FHZ and SM6PGP. Toward the end of the presentation there is a suggestion of a good way to setup the feed for circular polarization.
While this method of connecting the feed for circular polarization is quite comprehensive, for field use, it is way too complex. It is much simpler to use split transmit and receive lines, put the LNA at the feed, and use a small RF relay to protect the LNA during transmit. I tried to source suitable 12VDC SMA relays for my feeds, but the relays I was shipped turned out to be latching and not failsafe. Getting failsafe versions of these SMA relays is much easier at 24-28VDC. That is what I ended up doing. I rewired the control cable to the feed to add a pair of lines for 24VDC relay control to go along with the 12VDC LNA power. These two lines are enabled when I turn on the sequencer, and are dropped by the sequencer when going into transmit. At some point I’ll add a block diagram to this page to show exactly how I did it.
Purists will point out that maybe I did it wrong. The decision to provide more protection to the LNA’s was deliberate. I might have a minor amount of discontinuity to my circular polarity and/or impedance mismatch during transmit by having the RX port effectively unterminated. It is a conscious decision. On 1296 with up to 500w I have more than enough power to make up for the discontinuity. On 902 it seems to be relatively circular based on the few reports I have been given so far with less than 200w. I am hoping to be able to improve my transmit output level during this next year on 902.
The other choice that some may quibble about is that of circular polarization instead of linear with the ability to switch between horizontal and vertical. I agree that would be more compatible with most of the existing stations on 902. As a newcomer to 902, I am fighting the history. I have seen how easy it is to concentrate on the rest of the factors and not have to even think about faraday or polarization mismatch when using circular polarization on 1296. The fewer things that need my attention when I try to activate a new location, the better. The 902 and 1296 feeds are completely plug compatible in my system.
This summer I expect to add 2304 MHz. My new feed has already arrived from W2HRO to my home in Georgia. If all goes well with amplifier retuning, I will have 140w or more. It should be a lot of fun. I hope to put on many states, but I probably will not ever reach the level of dedication that KA6U has shown in making his activations. I hope to work all of you many times.
I was just barely able to make my first portable EME activation from DM56SS14HX at a campground named Quiet & Peaceful RV Park. I had driven from Weatherford, OK, leaving early in the afternoon of March 11th after having toured the Stafford Air & Space Museum and made it as far as a rest stop east of Albuquerque, NM, by late evening the 11th. I was trying to make it to near the Four Corners Monument area. I didn’t get into that area until mid-morning on Sunday, March 12th. I checked in to the RV Park and secured a space at the very westward end so as not to bother anyone with my very early morning activity. I was on the air for 902 EME at 08:00z Monday, March 13th.
I had been working with W5LUA and K5DOG in trying to figure out where it was legal to operate 902MHz EME with reasonable power. The limitations in New Mexico are many and seem severe in 47 C.F.R. § 2.106. There are a number of footnotes that limit 902-928 in New Mexico and nearby. Those footnotes specific to 902 MHz operations are:
US267 In the band 902-928 MHz, amateur stations shall transmit only in the sub-bands 902-902.4, 902.6-904.3, 904.7-925.3, 925.7-927.3, and 927.7-928 MHz within the States of Colorado and Wyoming, bounded by the area of latitudes 39° N and 42° N and longitudes 103° W and 108° W.
US275 The band 902-928 MHz is allocated on a secondary basis to the amateur service subject to not causing harmful interference to the operations of Federal stations authorized in this band or to Location and Monitoring Service (LMS) systems. Stations in the amateur service must tolerate any interference from the operations of industrial, scientific, and medical (ISM) devices, LMS systems, and the operations of Federal stations authorized in this band. Further, the amateur service is prohibited in those portions of Texas and New Mexico bounded on the south by latitude 31° 41′ North, on the east by longitude 104° 11′ West, and on the north by latitude 34° 30′ North, and on the west by longitude 107° 30′ West; in addition, outside this area but within 150 miles of these boundaries of White Sands Missile Range the service is restricted to a maximum transmitter peak envelope power output of 50 watts.
The last sentence in US275 is the tough nut to crack. This limits operation from not at all on 902-928 MHz or to <=50w PEP depending on location. Here is a graphic I worked up to show the exclusion zone in white and the 50w PEP limit areas inside the black lines:
I have these entered into Google Earth Pro on my logging laptop. If anyone wants an export of these points, please send me an email as listed on QRZ.com.
The approximate distance from the nearest 50w limit circle boundary to the RV park was a bit more than 13 miles. It seems a bit close, but there were very few other choices. I needed a place where I could connect to AC mains as my generator seems to make enough electrical noise to mask 902 MHz EME signals.
Closer to the four corners would also work, but this campground seemed like the best choice in terms of angles, trees, camper spots, and cost.
This was my first solo activation in the field. The RV park had no toilets or showers. I had to plan my activity carefully. I posted to the 902 MHz EME reflector on groups.io late in the afternoon that I would be on the next morning. I estimated that I needed 20 degrees elevation before I would have moon. It turned out that I only needed 10 degrees, but I used the extra time to get the dish better aligned to the moon. With better planning and more confidence from experience, I should be able to give everyone more lead time for my activations. My operating location looked like:
In all, 4 stations were logged. W5LUA, AC0RA, K0DAS and K5DOG completed with me.
Thank you to everyone that worked me or helped me. I was very tired and cold by the time I was finished. The overnight low was 31F and there was frost on the back of the truck. I slept in the back seat of the truck with a space heater powered from the AC mains, but it was not quite enough to keep the truck cab warm. I did not run the engine overnight as it seemed the RV park was focused on “quiet”. If I had a proper RV, I would have been much more comfortable. With as much effort as I had to put in, I made the decision to press onward toward the Utah/Nevada border. I had to stop in Salt Lake City the next day to chase down tire chains to fit the oversize tires on my truck to stay legal for the mountain passes in Oregon. I wanted to try to put UT/NV on from the Wendover and West Wendover area, but the morning I would have been the weather forecast included rain and 40mph wind gusts.
The original reason for me to drive from Georgia to Oregon was to visit my parents for an extended stay of more than a month. I will be getting on to 902 and 1296 EME from Oregon during this stay. I will make sure to choose better moon declination days while I am in Oregon. I will plan for some activations in May as I make my way back to Georgia.
It took awhile to get to this item, but last night I rough cut and put hooks on the piece that will become my desk in the truck. The desk board is about 21″ x 12″. I found a couple of (3/4″?) conduit hooks made quick and easy hooks to go over the top edge of the glove box and were thin enough to allow the glove box door to still close easily. It isn’t real pretty, but it is super quick to place and use.
The hooks are not enough to hold up the desk with the weight of the laptop. I’ll add a cord or small rope with a hook to the passenger side grab handle to support the right rear corner. The plywood is at least 1/2″ thick and is sufficiently rigid that one support cord will be enough.
I built a rack for the radio equipment that would live inside of the truck. It is approximately 24 inches long, 11 inches deep, and the ends are 14 inches tall. I marvel at the capabilities that can be placed into that small a package.
160m through 23cm operation on all the amateur bands. Check.
Decently capable SDR radio with super easy transverter interfacing. Check.
GPS disciplined 10MHz clock reference with 4-way splitter. Check.
USB hub and USB power ports. Check.
Azimuth and elevation rotor control tied to the USB hub. Check.
AC and DC power distribution. Check.
The rack size was a design compromise to fit the equipment planned. It needed to be light enough that I could move it easily, and fit on top of the center console so that I can access the front controls while sitting in the passenger seat. Contrary to what others have assumed, it is not rational to operate EME Rover in ‘run-and-gun’ style from the driver’s seat. There is more room in the passenger seat for the laptop and second monitor.
It’s all tied down so that none of the parts bounce or move within the rack during transport. It requires 10 cables disconnected to be removed from the truck. The cables are:
PTT to Amplifier
RX Enable to LNA and RX Relay
USB Cable from hub to Laptop
In roving operations, I can leave 7 of the cables connected when the rack is stowed into the back seat. The two coax cables and the laptop USB cable need to be disconnected to move the rack to the rear. When in the back seat, I make it wear a shoulder strap, but I may change that to straps that make use of the child seat loops built into the rear seat by Dodge.
This post is not complete. It will continue to change. I will remove this paragraph when I am done. It will be a long one. It has been backdated to the completion date of the amplifier as I used it during the November 2022 weekend of the ARRL EME contest.
As I started to work through the list of major modules needed for an EME rover, I quickly found that lead times for 1296 MHz amplifiers were too long for my first hoped departure of mid-November, 2022. Significant amplifiers for 23cm are also a bit pricey, and my first choice from complete turn-key W6PQL amplifier is not available for the foreseeable future. Looking through all the options I noticed that KB7Q had rolled his own amplifiers multiple times using W6PQL pallets.
I chose to order the fully assembled 1296MHz pallet and support circuits that I thought I would use. I floundered around a bit figuring out the configuration. I ended up with a quite capable amp. I used W6PQL’s control board and 50V FET switch in my amplifier. These used in the amplifier so far, but I bought more modules and intend to upgrade further. I had some significant coaching from KB7Q who was very helpful answering some of my questions about how to proceed. I like Gene’s KISS approach. The schematic is from his August 2021 presentation to NTMS:
My amplifier ended up a bit more complex than Gene’s, but it was still close to his ideal. I prefer to use only one power supply voltage to an amplifier. KB7Q’s method is very simple, but requires 50VDC and 12VDC supplies. I intended to mount the amplifier in the covered bed of my truck. I reasoned that the heat generated might make the truck interior a bit warm and moving the amplifier closer to the dish would reduce coax losses.
The W6PQL control board has many functions available. I liked the idea that thermal fault inhibit was so easy to implement. The temperature sensor is included in his control board kit. The board is setup to provide bias to the power FET switched with PTT. It is also able to provide low current 12VDC when the TIP102 regulator is installed. A word of warning though, using the TIP102 circuit really needs a current limiting resistor as the supply is drawn from the 50VDC. For the 50VDC reduction to 13.5VDC, a 25 ohm 25 watt resistor is recommended. I missed that detail in my first readings of the control board documentation. Mail order parts to the rescue.
<Brian amplifier version photo and schematic to be inserted here>
When I was reviewing the cabinet and heat sink requirements I saw what W6PQL says this about heat sinks at the bottom of his ‘parts I can supply‘ page, “I no longer supply heat sinks as a part, but you can still purchase the material directly from www.heatsinkusa.com. The amplifiers use the 10.080 inch extrusion, which weighs roughly 1 pound per inch of length. For amplifiers up to 1kw, and for the 1.5kw VHF amplifiers, order a 6-inch length. For 1.5kw HF amplifiers like the HF2000, you will need a length of 10 inches…or you can use two of the 6-inch pieces. Use the drilling templates supplied with your amplifier kits as a guide to drill and tap.” So the candidate heat sink should be roughly 6 lbs. of aluminum (or better) and roughly 6 inches by 10 inches.
W4ZST helped me with so many parts of this amplifier. I would not have been able to complete it so quickly without his help. He located a selection of cabinets and heat sinks to choose from to house and help cool the pallet.
“Candidate 3″ shown above is what I decided to use. At 9″ by 15″, with a thicker base material and lots of fins, Bob, W4ZST, and I measured the weight of this one as 13 lbs. I realized this was more than enough material to dissipate the heat generated by the pallet. This heatsink was originally a commercial ~453MHz transmitter combiner with 3 or 4 inputs. From the interior I was able to salvage dummy loads and RG213 double shielded N-male jumpers. A bonus feature was the 19” rack mount face that I might use in the future depending on how I “permanently” mount the amplifier.
<Case selection and preparation to be added here>
<More details and performance…>
On his page, https://www.w6pql.com/high_power_amplifier_for_1296.htm, W6PQL notes that Eccosorb is used, “…to dampen resonances produced inside cavities like the one created when the cover is in place.” I had some similar material and put it in case cover opposite the RF pallet.
To paraphrase JFK, ‘We choose to bounce radio off the moon, not because it is easy, but because it is hard…’ It is as much for the challenge as it is for making the contacts. To make any EME contacts is non-trivial. To make many is a real challenge. To make many EME contacts, move the whole station, and do it again is a seemingly insurmountable set of challenges.
This entry is backdated to the date that the seeds of my EME yearning sprouted. I credit the Southeastern VHF Society 2001 Conference as that moment. I did not attend. I was driving to Chicago from Atlanta with my wonderful wife (N9KHC) and first child (KK4JJT). We stopped on the drive for a few minutes to say hello to friends at the conference. We couldn’t stay! I sorely wanted too, but we had many people traveling into the Chicago area to meet up with us for the baptism of Claire, our oldest daughter. I did manage to buy a copy of the proceedings.
Oh what wonders were in those proceedings! Some of the presentations that piqued my interest:
EME Basics, by Bob McGraw, K4TAX
23cm EME, by Bruce Clark, K0YW & Jay Liebermann, K5JL
50 MHz Eleceraft K2 with Internal DEMI (transverter), and VP2M DXpedition, by Dick Hansen, K5AND (When Dick decided to sell that K2 it became mine. Thank you Dick!)
222 EME, by Ray Rector, WA4NJP
Oh my! 222 EME. That last one really clicked. But as time went on, I wanted to do it the hard way. I wanted to do 222 EME roving. I never did do it. Two more children, lots of work travel and the rest of a busy life got in the way. I did start collecting parts and equipment. I justified it by using much of the 222 gear to improve the station used for W4NH contest efforts. That was my start.